There has been a need for a long lived high current density cathode to operate in microwave devices. Heretofore, attempts at making such cathodes that have been most successful have involved impregnating a suitable matrix such as a porous tungsten billet with a mixture of barium oxide, calcium oxide, and aluminum oxide and then sintering the billet at a temperature at which the impregnant melts. This provides the barium atoms that are needed for the generation of electrons. The difficulty with these cathodes is that they usually have a maximum current density capability of 2 to 4 amperes/cm.sup.2 at 1050.degree. C. which density is too low.